1. Field of the Invention
This invention relates to a fixture for holding a number of spade drills of various size, one at a time, on a reciprocable grinding table to facilitate the sharpening of the spade drill.
2. Prior Art
Spade drilling is a relatively new art, but as the art has emerged from various commercial sources, various problems have already arisen in connection with the sharpening at original manufacture and the resharpening after use in the field. In some instances, there has been considerable overhang of the blade, necessitating a slower feed of the grinding wheel, and some sacrifice in accuracy. Further, as such spade drills or blades must be ground on two sides, the labor in fixing or locating the spade drill for work on one side has had to be repeated in order to sharpen the other side of the drill. Because of the complexity of the configuration of the cutting end of a spade drill, the various adjustments and settings have not been easy and often times have not been accurate. Repeatability has at times been difficult to achieve. Further, more sophistication can be expected at the factory than one might find in the facilities of the user, an example of which is the control of the skew angle, not always heretofore duplicated after use. Because of the complexity and sophistication involved, the use of skilled personnel has been necessary to operate the tool grinder.